Substituted thioureas as dyestuff intermediates



Patented Nov. 4, 1952 v SUBSTITUTED THIOUREAS. AS

' INTERMEDIATES Henry G. Derbyshire, Johnson City,"N'- Yo a signorto General Aniline =&;1Film; Gorporatiom New York, N. Y., a corporations-of, Delaware,-

No Drawing. Application Deceinber-lfi, 1949,

Serial N0. 133,4'72

, 6- Cla m This: invention relates to-' substituted thioureas which are- 0f value as dyestuif intermediates.

The object of the present invention is to provide substituted thioureas as Y dyestufi intermediates for thesynthesis of cyan-ins dyes capable. of sensitizing gelatino silver halide emulsions.

Qther-objects and advantagesoii this invention,.will become apparent" by reference tothe followingspecification in which its-preferred des tails and embodiments are described:

These and other objects are accomplishedby heating a cyclammoniu-m quaternary salt having a reactive amino group in the aor 'y-position to the quaternary nitrogen atom with an alkyl or aryl isothiocyanate in the presence of a basic condensing agent. The reaction takes place with the liberation of an acid and yields the thiourea derivative. The resultingproduct may be (1) alkylated with; an alkyl or aralkyl ester, or (2) heated with an a-halogen acid, a-dihalogen acetic acid, or with an a,-halogen propionic acid to yield thiazolonecyanine dyeswith a nitrogen chain atom. The product obtained from the second reaction by: treatment with a-halos n acetic ac d may-;- b further treated with cyclammonium; quaternary s t o he pe commonly-employed; inwyanine dye synthesis to yieldazatrinuqlear cyaninedyes:

The reaction involved; while. utilizing an mam;

mini-n0 sub t ut d cyclamm niumqua ernary salt and an alkyl .or. an so hiocyanate in the presence of a basic-condensing agent. isillustrated, bythe followingequation:

0 or 1, X represents an acid radical, e. g., chloride,

bromide, iodide, or alkyl sulfate, alkyl p-toluenesulfonate, or perchlorate, and Z represents the residue of a heterocyclic nitrogenous nucleus of the type used in cyanine dyes, e. g., oxazoles, thiazoles, selenazoles, and their polycyclic homologues: such; 3511111056 of thebenzene, naphtha lene, acenaphthena. and ganthracenexsen i pyridine, and. its. polycyclichomologues, such as quinoline and aand;, -naphthaqu n 1in s. Peri naphthiazolesr indolenines, diazines,

-hlWfi-Q'I-fiWQlfiL ,oXazoline pyrmlines, thia zol nes and selenazolines (the p ly yc ic com-- p unds at these series be ng Substitutedif desired the carb ycli r ngs wi h o r more con: v nti nal roups ucha alkyl, r ryl, asbelom amino, hydroxy; alkoxy, i, e., methoxy, ethoxy, etc., and methylenedioxygroups, orby halogen: atoms, i, e., chlorine, bromine,- etc) Any ne of he known ypes of cyclammobi-um:

uaternary. lts havi g; the: p cific.- reactive: amino group commonly; employed: for use in the manufacture of cyanine dyes maybeemployed; in; the process of the present invention. As representative examples of'such salts, the followin may be mentioned:

Zeamino s 5,6 ucyclopentyli'dineadioxys-benzthi zole-ethylpetoluenesulfonate zeam-ino .-J 5126. dimethoxyebenzthiazolesethylspe toluenesulfonate:

The following are examples of suitable" alkyh aryl and aralkyl isothiocyanates which may be condensed with the cyelammonium quaternary salts in the presence of a basic condensing agent:

methyl isothiocyanate ethyl isothiocyanate propyl isothiocya-nate isopropyl isothiocyanate n-butyl isothiocyanate allyl isothiocyanate benzyl isothiocyanate, phenethvl isothiocyanata ph nyl. isothiocyanate plyl. 'isothiocyanate -tolyl isothi.ocyanate:

n-chl r phenyl is hiocyanate The substituted thioureas-are prepared by" dissolvinga molecular equivalent of a -cyclammonium quaternary-salt havingthe specified reactive amino group, and a slight excess of a su h as: pyrimidines, and: quinazolines, diazoles, (e,- g;.

molecular equivalent of an alkyl, aryl, or aralkyl isothiocyanate in a sufficient quantity of a heterocyclic nitrogenous base, such as pyridine, dimethylpyridine, ethylpyridine, ethylmethylpyridine, trimethylpyridine, quinoline, and the like. To this solution a small quantity of an organic base, such as an alkylamine, e. g., dimethylamine, diethylamine, trimethylamine, triethylamine, and the like, is added and the solution is heated either at the steam bath or reflux temperature for a period of time ranging from 15 minutes to 1 hour. The crystals which form during this time are filtered ofi, washed with alcohol, and dried.

The reaction product obtained may be alkylated by heating a molecular equivalent of the product with about A; to 4 molecular equivalents of an alkyl or aralkyl ester usually employed in the cyanine dye art, such as, for example, dimethyl or diethyl sulfate, benzyl iodide, methyl p-toluenesulfonate, and the like, in a closed vessel at a temperature ranging from 120-l60 C. from 2 to 6 hours. The reaction mixture is cooled, boiled with acetone, alcohol added, and the crystals precipitated with ether. The final product is purified by precipitation with ether from a methanol-acetone solution.

The following examples describe the preparation of some of the substituted thioureas. It is to be understood that the following examples are merely illustrative and that the invention is not to be regarded as restrictive thereto.

Example I s O=N i N )zHs N- (B-ethyl-2-benzothiazolylidine) -N-pl1enylthiourea 5.5 grams of 2-aminobenzothiazole ethiodide and grams of phenyl isothiocyanate were dissolved in mls. of hot pyridine. The solution was heated slowly until its temperature reached 130 C. Upon cooling to C., a yellow solid crystallized which was filtered 01f, washed with water, dried, and purified by recrystallization from methanol. The product was dried at 85 C. 5.4 grams of a purified product were obtained which melted at 158 C.

N4 3-etl1yl-6-etl1oxy-2-benzothiazolylidine-N phenylhiourea 8 grams of 2-amino-6-ethoxybenzothiazole ethiodide and 5 grams of phenyl isothiocyanate were dissolved in 10 mls. of boiling pyridine. The resulting solution was stirred and slowly heated to 150 C. while permitting the pyridine to distill all at this point. Heating was discontinued, but stirring was kept up until the reaction mass was cooled to 25 C. A yellowish solid separated 4 which was washed with two 25 ml. portions of water, then triturated with 20 mls. of methanol and filtered. After consecutive washings with water and methanol, the solid was dried overnight at C. 6 grams of a purified product were obtained which melted at 177-180 C.

Example III 02H CHzCH=CH1 N-(3-ethyl-6-etl10xy-2-benzothiazolylidine)-N-allylthiourea '7 grams of 2-amino-6-ethoxybenzothiazole ethiodide and 5 grams of allyl isothiocyanate were heated together in 5 mls. of boiling Pyridine. Heating was continued until the internal temperature reached C. The reaction mixture was cooled to room temperature and poured into 10 mls. of water. The yellow solid which separated was triturated with three fresh 10 ml. portions of methanol, filtered, washed alternately with Water and methanol and dried. The purified product melted at 119-122" C.

Example IV N- 3-methyl-2-benzothiazolylidine -N -phenyltl1iourea This product was prepared from 5 grams of 2-aminobenzothiazole methiodide and 5 grams of phenyl isothiocyanate by following the procedure of Example I.

N 3,4-dimethyl-2-thiazolylidine) -N'-pl1enylthiourea 100 grams of 2-amino-4-methylthiazole dimethylsulfate and 5.7 grams of phenyl isothiocyanate were heated slowly together until the temperature of the reaction mixture reached 140 C. At this point, heating was discontinued and the mass was stirred constantly until it reached room temperature. Crystals separated when the mass was diluted with a mixture of 200 mls. of equal parts of water and isopropanol. The crystals were filtered off, washed in isopropyl alcohol, and dried.

The substituted thioureas can also be prepared 'by reacting the amino-substituted cyclammonium quaternary salt with an alkyl N-phenyldithiocarbamate, such as methyl N-phenyldithiocarbamate or ethyl N-(p-tolyl) dithiocarbamate, as illustrated by the following example:

Example VII N 3-ethyl-2-napl1tho [2,1] thiazolylidine) -N-phenylthiourea 9.2 grams of methyl N-phenyldithiocarbamate and 17.8 grams of 2-aminonaphtho[2,1lthiazole ethiodide were dissolved in 60 mls. of pyridine and heated to 145 C. Yellow crystals separated upon cooling, which were purified by alternate washings with water and methanol. The purified product melted at 203 C.

The dyestuff intermediates prepared according to the preceding examples may be utilized in the synthesis of various types of optical sensitizing dyes, such as trinuclear cyanine dyes, and the like.

I claim:

1. A substituted thiourea dyestuff intermediate characterized by the following formula:

wherein R represents a member selected from the class. consisting of alkyl, aryl, and aralkyl groups, R1 represents a member selected from the class consisting of lower alkyl, allyl, aryl, and aralkyl groups, n represents an integer of from to 1, and .Z represents the atoms necessary to complete a heterocyclic nitrogenous ring system. 2. A substituted thiourea dyestuft intermediate characterized by the following formula:

6 3. A substituted thiourea dyestuff intermediate characterized by the following formula:

4. A substituted thiourea dyestuif intermediate characterized by the following formula:

5. A substituted thiourea dyestufi intermediate characterized by the following formula:

6. A substituted thiourea dyestuff intermediate characterized by the following formula:

HENRY G. DERBYSHIRE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,093,214 Schrader et a1 Sept. 14, 1937 2,312,040 Kendall et a1. Feb. 23, 1943 2,394,067 Kendall et a1. Feb. 5, 1946 2,425,774 Wilson Aug. 19, 1947 2,464,785 Thompson Mar. 22, 1949 2,536,986 Thompson Jan. 2, 1951 OTHER REFERENCES Schneider et al., Berichte, vol. 57, pages 522-532 (1924). 

1. A SUBSTITUTED THIOUREA DYESTUFF INTERMEDIATE CHARACTERIZED BY THE FOLLOWING FORMULA: 